Fan construction



July 21, 1931. lw. sHuRTLEm-f 1,815,529

FAN CONSTRUCTION I Filed Feb. s, 1929 2 sheets-snm 1 l rv July 21, 1931. w. sHuRfrLsFF Fim cnsmucuou Filed Feb. 8. 1929 2 Sheets-Sheet 2 Patented July 2l, 19.31

UNITED .STATI-:s

PATENT OFFICEv WILFRED SHURTLEFF, F MOLINE, ILLINOIS, iASSIGNOB TO HERMAN NELSON COB.- PORATION, OF MOLINE, ILLINOIS, A. CORPORATION OF vILLINOIS FAN CONSTRUCTION Application led February 8, 1929. Serial No. 388,404.

rThis invention relates to fan constructions.

An object of the invention is to provide a fan construction intended for use in connec- 'g tion with a low torque inexpensive motor, and wherein the fan structure is so designed as to be able to force air against considerable pressure. 1

Another object of the invention is to vpro- 10. vide a fan construction of this type wherein the fan blades are made up of sheet'metal and are so designed as to provide noiseless operation and higher eiiiciency than fans as/ now used. y

Stilll another object of the' invention is to provide ya fan construction which includes as elements, -a member having an o ening therein and a fan, the bladesl of the an being arranged in such fashion as to provide two different diameters axially of the fan one-diameter being of such size as to'it w1thin the opening and the other diameter being larger than the opening anddisposed outside of the same whereby more air is moved and high efficiency produced. i

Still another object of the invention is to provide a fan wherein the larger diameter of the same is aiiorded by forming extended tips along the leading edges of the blades l thereby confining the increased diameter volgl the fan to a localized extent outside of the opening in the associated member, and increasing the volume of air handled with onl a small area of the fan acted upon by baci pressure.

Itis also a further object to provide a fan wherein each blade is provided with small radius curves across its width, said curves being connected by a rid e portion which strengthens theblade, and the provision of the small radius curves ermitting the use of an exceptionally wide Bladewithout excessive pitch, the width of the blade and the manner of curvature increasing the eiiiciency of the fan in forcing air against pressure.

, Thefan further contemplates an arrangement wherein the trailing 'edge of each' blade is cut on a bias across the .curved portions thereof resulting in a screw effect being im- 50 parted to the blade which is highly useful stream line formation'at the intake side of the fan which results in reducing noise and makes for high efiiciency.

Other and further objects of the invention will more clearly appear from' the description and claims hereinafter following.

In the drawings formin a part of this specification, Figure 1 is a ront elevational v1ew of the fan construction embodying my invention.` Figure 2 is a fragmentary, vertical section of the invention, corresponding to the line 2 2 of Figure 1 and showing the fan blades in elevation. Figure 3 is a crosssectional view taken through the base portion of one of the fan blades and corresponding substantially to the line 3-3 of Figure 1. Figure 4 is a sectional view taken through the fan blade and corresponding` substantially to the line 4 4 of Figure 1. igure 5 is a sectional view corresponding substantially to the line 5-5 of Figure l. Figure 6 is a sectional view corresponding to the line 6-6 of Figure 1. And Figure 7 is an enlarged edge view of one of the fan blades detached from the fan.

As show n in the drawings, an enclosure is provided indicated by the reference character 10. The enclosure 10 preferably is rectangular in form andis adapted for the reception ofV a radiator indicated at 11, the forward portion of the casing 10 being open and adapted to discharge into a room to be.

The fan proper includes a s ider 14 rigidly mounted upon a driving sha 15, the spider in this instance, being provided with six legs vindicated at 16, and each of said legs 1s twisted at about 45 with reference to the longitudinal axis of the shaft. To each of the Alegs 16 is secured by. suitable rivets or other means indicated at 17, a fan blade. All of the fan blades are of exactly similar construcl tion and mounted in the same manner, and a detailed description of only one blade will be given herein.

Each fan blade is made up of a plate formed from sheet metal, and comprises a body portion which is curved across its width in two arcs 17 and 18 providing concave portions extending longitudinally of the body portion, one near the leading edge, and one adjacent the trailing edge of the blade, and

both concave portions being curved in the.

same direction. The concave or arcuate por)- tions are separated by a ridge-like portion 19, the latter imparting considerable strength to the sheet metal blade as will be appreciated. By reason of the provision of the two concave portionsin the blade, it will be understood that an extremely Wide blade may be utilized without the necessity for providing a single deep curve from the leading edge to the trailing edge, which would weaken the blade structure and render the pitch of the blade entirely too great.

The trailing edge 20 of the blade is cut on a bias or incline from the point indicated at 21 of the portion of the blade adjacent the center of the fan to a point 22 at the outer end of the blade, the trailing edge extending across the concave portion 18 and hence imparting to the blade a screw-like configuration which serves to equalize the delivery pressure of the fan throughout the surface of the blades, that is, the pressure delivered adjacent the center of the fan will be the same as that delivered at or adjacent the outer ends of the blades.

The leading edge 23 of each blade is curved throu hout its extent as indicated at 24: so that t e extremity 25 of the curved portion is disposed within the outermost surface 26 of the intake side of the fan. This affords a stream line engagement with the air com-v parable to that afforded by the heavy propeller type of fan used principally in airplane construction. It reduces noise and in creases eiiiciency.

The leading edge of the fan at its outer end is provided with an extended tip portion 2 curved in conformance with theconcave po tion 17 and extending beyond the outer end 28 of the blade proper, the Width of the tip preferably being about a third of the -width of the blade as bestshown in Figure 1. This affords a construction which provides a fan with two diameters, the smallerofwhich is vof such size as to be disposed Within the opening l2 of the casino' 1,0, whereas the larger diameter as'aiorded by the tips of thefan is disposed outside of the openin and provides, in effect, a fan larger than t e opening 12 resulting in an increase of air'volume without waste of power.

As above pointed` out, the fan blades may be of relatively great" width, and strength- 05 ened'by the ridge portion which joins the curved portions, and in conjunction with the tapered trailing edge provide the screw effect for equalizing the pressure developed by the fan. The extreme width of the blades in conjunction with the ti portions provide the two diameter fan which co-operates with the casing in increasin the air volume. Thus it will be apparent t at a lhighly efficient fan having sheet metal blades is produced having great strength, capable of operation with a motor having a low in-put such as must be used in the situation referred to and wherein equalized delivery of air is obtained against pressure without the development of undesirable power losses.

'While I have herein shown and described what I now consider the preferred manner of carrying out my invention, the same is merely illustrative and I contemplate all changes and modifications which come within the scope of the claims appended hereto.

I claim 1. In a fan construction of the character described, the combination with means providing an opening; of a fan disposed in said opening and having a lurality of blades, each of which is moun e'd to position its trailing edge in a different plane of rotation than its leading edge,r and each of which is curved across its Width to provide longitudinally extendinfg` concave portions curved in the same irection, the trailing edge of said blade extending across one of said concave portions at an angle to the leading edge to proiide a screw effect, and the leading edges o said blades being extended beyond the ends of said blades Within said opening and disposed outside of the means defining said opening.

f 2. A fan having a lurality of blades, each of which is formed of, sheet metal and mounted dto position its trailing edge in a different plane of rotation than its leading edge, each blade being curved from its leading to its trailing edge upon two arcs providing longitudinally extending concave ortions, the later being connected by a ridge portion extending inthe reverse direction, the trailing edge of said fan converging outwardly at an angle toward the plane of rotation of the leading edge and across one concave portion to rovide a screw effect, and each blade at the eading edge being extended beyond the outer end thereof to provide a larger diameter at the leading edge of the fan.

-3. A fan havingV a blade of sheet metal of substantially uniform thickness formed with a leading edgevcurved inwardly of the outermost ,intake portion of the blade, and a trailing` edge angularl disposed with respect to said leading e ge.

4. A fan comprising a plurality of radially extending sheet metal blades, each of which is made u of sheet metal of substantially uniform t ickness and curved across and extending longitudinally beyond thel outer end of said blade to provide a tip.

5. In a fan of the class described, the.

combination ofE a. plurality of substantially radially disposed blades, each curved transl versely from its leading edge to its trailing edge and having its trailing edge at an angle to its leading edge to provide a screw-like formation to said blade, each blade diverging in Width from its outer end to its inner end, and means supporting said blade for rotation With their trailing edges in a different plane than their leading edges.

6. In a fan construction of the character described, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having its axis concentric with said opening and havin a plurality of radially extending blades, eac blade having the major-'portion' of its body Within the conlines of said opening and behind the marginal plane thereof and each blade having a tip projecting radially beyond the body of the blade and outside of the marginal plane of the Vopening and radially beyond the margin of the opening. i

7 In a fan construction of the character described, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having:A its axis concentric vvith said opening and having a plurality of radially extending blades, each blade having its cross diameter oblique to the plane of rotation of the fan and having the major portion of its body Within the confines of said opening and behindjthe marginal plane thereof, and each blade having a tip projecting ra-l dially beyond the body of the blade and outside of the marginal plane of the opening and radially beyond the margin of the opening.

8. In a fan construction of the character described, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having its axis concentric with said opening and having a pluralityof radially extending blades, each blade having its cross diameter oblique to the plane of rotation of the fan, andy having its leading edge extending substantially parallel with scribed, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having its axls concentric with saidopening and having a plurality o f radially extending blades, each blade having the major portion of its body Within the confines of said opening and behind the marginal plane thereof, and each blade having a tip projecting radially beyond the body of the blade near its leading edge and outside of the marginal plane of the opening and radially beyond the margin of the opening. Y

l0. In a fan construction of the character described, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having its axis concentric with said opening and having a plurality of radially extending blades, each blade having its cross diameter oblique to the plane of rotation of the fan and havlng the major portion of its body Within the contines of said opening and behind the marginal plane thereof, and each blade having a tip projecting radially beyond the body of the blade near its leading edge and outside of the marginal plane of the lopening and radially beyond the margin of the opening.

1l. In a fan construction of the character described, the combination of means defining a circular opening presenting its margin in a uniform plane, a fan having its axis concentric with said opening and having a plurality of radially extending blades, each blade having its cross diameter oblique to the plane of rotation of the fan, and having its leading edge extending substantially parallel with such plane of rotation, and having the major portion of its body Within the coniines of said opening and behind the marginal plane thereof, and each blade having a tip projecting radially beyond the body of the blade near its leading edge and outside of the marginal plane of the opening and radially beyond the margin of the opening.

In Witness that I claim the foregoing I have hereunto subscribed my name this 29th day of January 1929.

- WILFRED SHURTLEFF.

such plane of rotation, and having the major `port-ion of its body within the confines of said opening and behind the marginal plane thereof, and each blade having a tip projecting radially beyond the body of the blade and outside of the marginal plane of the opening-and radially beyond the margin of the opening,

9. In a fan construction of the character de- 

